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Author Topic: Why does heating increase mass?  (Read 42756 times)

Offline Lamprey5

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Why does heating increase mass?
« on: 12/01/2011 12:30:03 »
Ryan Chown  asked the Naked Scientists:
   
Hey there,

I'm an avid listener to your podcasts [nofollow], and I've got a question for you.

I've read that when the temperature of matter increases, it's mass increases. For example, when you heat up a gold bar, it weighs a little more - but by an incredibly small amount.

Despite how small the difference in mass is after heating the gold bar, I would like to know the process behind how this really happens, if in fact it does increase in mass. (I imagine that the increased kinetic energy of the gold atoms translates into a greater mass, but I can't wrap my head around the process behind it.)

Take care,

Ryan

Hamilton, Ontario, Canada
17 yrs old

What do you think?
« Last Edit: 12/01/2011 12:30:03 by _system »


 

Offline CliffordK

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Why does heating increase mass?
« Reply #1 on: 12/01/2011 13:10:49 »
Heating causes thermal expansion.

The mass remains the same.

The volume increases.

And thus the density decreases. 

So, for example, a bar might appear longer when heated, but it will weigh the same.

Quantum physicists will discuss a relationship between matter and energy (E=mc2).  But, only on a scale of a very large amount of energy.
 

Offline imatfaal

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Why does heating increase mass?
« Reply #2 on: 12/01/2011 17:26:22 »
Hello Ryan

As the energy within a an object increases - ie by heating it up - it will increase in mass.  The difference, as you guessed, will be incredibly small.  Einstein's theory of General relativity would lead us to believe that the kinetic energy of the individual atoms would make a contribution to the gravitational mass - thus a hot brick weighs more than a cold brick. 

To get your head round it will take a lot of work - wikipedia has a good explanation of mass in general relativity but it would still be heavyish going. 
 

Offline yor_on

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Why does heating increase mass?
« Reply #3 on: 13/01/2011 12:21:33 »
I also find it strange Ryan. But it is true. One could assume it has to do with 'kinetic energy' as the material gets heated, but then we have the example with having two springs, compressing one and locking it in that position. From that on the locked spring will have a greater mass than the unlocked one, as I understands it.

You might want to think on how a black hole is expected to be created. In fact it have to be the same, or at least a very similar, principle. To make one you just have to compress matter, you can't make one by making it move, only by compressing it. So it should have to do with how the atoms act as they get 'compressed' together.

"The mass of a proton is about 938 MeV. It consists of three quarks, each of which have a mass on the order of 3 MeV (more or less, not very accurate.) There is a huge discrepancy between 938 and 9. The remainder of the mass of the proton is the potential and kinetic energy of the gluons holding the whole thing together. The correct vision of a proton is a little subatomic gluonic lightning storm, buffeting three nearly insignificant quarks. "

And the 'gluons' is what we believe to be there, as seen indirectly in high energy accelerators. Somehow we all on that very small level become indeterminate and impossible to 'pinpoint'. It's weird :)
 

Offline Lamprey5

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Why does heating increase mass?
« Reply #4 on: 24/01/2011 20:40:38 »
What I really want to know is how an increase in an object's energy will increase its mass. Even in the simplest closed system, an example of how energy converts into mass would help.
When you heat up a gold bar, for it to increase mass would mean it curves space-time more than it did at its initial cooler temperature, correct?
This makes sense but is there some sort of quantum particle exchange going on when the gold bar heats up that makes the energy turn into mass (and vice-versa when the bar cools down)?
Maybe the discovery of the Higg's boson would explain for this?
My wild guess would be the photons of heat radiation converting into Higg's particles, which is predicted to "give objects their mass".
 

Offline jartza

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Why does heating increase mass?
« Reply #5 on: 24/01/2011 22:15:30 »
Well, they say mass-energy curves space time.

And they say pressure curves space-time.

Also they say stress curves space-time (I suspect stress might be same as pressure)

And then they say momentum curves space-time.

 

Offline CliffordK

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Why does heating increase mass?
« Reply #6 on: 24/01/2011 22:57:22 »
Did I bring up Einstein?  [xx(]

Perhaps one way to look at "heating" would be a pure Infrared/EM model (in a vacuum).

If an object absorbs more IR/EM that it gives off, it will tend to heat up.
If an objects releases more IR/EM than it it absorbs, it will tend to cool down.
And if the two are balanced, then the temperature would stay the same.

So, the question should be what the absorption/release of IR/EM ENERGY actually does, other than causing molecules to vibrate.

Are photons truly massless, in which this is just converting radiation energy to molecular vibration energy.  Or...  do the photons actually have a mass, in which case this is the photons are being absorbed & released, and thus a mass absorption/release.
 

Offline jartza

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Why does heating increase mass?
« Reply #7 on: 25/01/2011 13:03:01 »
A very very fast moving object curves space-time mainly by its momentum.

A very very fast moving object onto which a co-moving lamp is shining light, is
curving space-time an amount that is constantly increasing. The increasing
space-time curving ability is due to increasing momentum.


 

Offline lightarrow

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Why does heating increase mass?
« Reply #8 on: 25/01/2011 14:49:53 »
What I really want to know is how an increase in an object's energy will increase its mass. Even in the simplest closed system, an example of how energy converts into mass would help.
Because energy *is* mass, in a stationary system. No "convertion" at all.
 

Offline Lamprey5

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Why does heating increase mass?
« Reply #9 on: 25/01/2011 18:54:42 »
Could you refine your statement that "energy is mass"? I understand mass to be "that which occupies space and possesses rest mass, especially as distinct from energy" (Oxford English Dictionary). To increase an objects temperature doesn't change the amount of matter in it, but it's mass increases, correct?
 
How does energy and mass curve space-time similarly?
 

Offline simplified

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Why does heating increase mass?
« Reply #10 on: 25/01/2011 19:05:22 »
What I really want to know is how an increase in an object's energy will increase its mass. Even in the simplest closed system, an example of how energy converts into mass would help.
Because energy *is* mass, in a stationary system. No "convertion" at all.
Is energy of Earth the part of gravitation mass of Solar system ?
« Last Edit: 25/01/2011 19:21:12 by simplified »
 

Offline simplified

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Why does heating increase mass?
« Reply #11 on: 25/01/2011 19:15:20 »
A very very fast moving object curves space-time mainly by its momentum.

A very very fast moving object onto which a co-moving lamp is shining light, is
curving space-time an amount that is constantly increasing. The increasing
space-time curving ability is due to increasing momentum.



Photon has momentum.Does photon curve space-time?
 

Offline jartza

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Why does heating increase mass?
« Reply #12 on: 26/01/2011 09:28:28 »
Oh yes, they say that photons curve space-time with their momentum.

 

Offline jartza

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Why does heating increase mass?
« Reply #13 on: 26/01/2011 10:16:37 »
Could you refine your statement that "energy is mass"? I understand mass to be "that which occupies space and possesses rest mass, especially as distinct from energy" (Oxford English Dictionary).

I respect Oxford English Dictionary. It tells what a word means, whether it makes sense or not. "Mass possesses rest mass"
 

Offline jartza

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Why does heating increase mass?
« Reply #14 on: 26/01/2011 11:01:18 »
Let's say particles A and B have enormous mass-energy, because they are moving very very fast, at the same direction.

It is very easy to keep these two enormous mass-energies apart.

BUT if we try to pull these particles apart, they will resist with large gravitational force.



Oh dear I made a mistake.The large energy that is required to pull fast moving objects apart turns into fast moving potential energy. The inertia of gravitational energy is responsible for the large force. Not gravitational force.
« Last Edit: 26/01/2011 15:43:13 by jartza »
 

Offline lightarrow

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Why does heating increase mass?
« Reply #15 on: 26/01/2011 13:10:07 »
Could you refine your statement that "energy is mass"? I understand mass to be "that which occupies space and possesses rest mass, especially as distinct from energy" (Oxford English Dictionary). To increase an objects temperature doesn't change the amount of matter in it, but it's mass increases, correct?
Do you think only particles with non zero mass can give mass to a system? It's not, mass is not additive. It means that the total mass of a system of two particles with mass m1 and m2 is not m1 + m2.
Furthermore, where does the mass of a massive particle come from? Part of a mass of an atom is in the EM fields between nucleus and electrons. Most of the mass of a proton or a neutron is in the strong force fields between quarks.
A system of two photons not traveling in the exact same direction has mass.
A static electric field has mass.
...
The fact that mass, according to Oxford dictionary is "that which occupies space and possesses rest mass, especially as distinct from energy" is not very explicative...
Quote
How does energy and mass curve space-time similarly?
Because they are the same thing: the mass of a stationary system *is* that system's energy (divided by c2). The mass of a massive particle *is* the sum of all the energies of the different components of that particle, if it's made up of other things (energy is additive).
« Last Edit: 26/01/2011 13:30:54 by lightarrow »
 

Offline lightarrow

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Why does heating increase mass?
« Reply #16 on: 26/01/2011 13:20:11 »
Is energy of Earth the part of gravitation mass of Solar system ?
1. If with "energy of Earth" you mean its "internal" energy, without considering its "gravitational potential energy", then it's Mc2, M = Earth's mass.
2. In General Relativity gravity it's not a force, so there isn't any "gravitational potential energy". However, if it was another kind of force field, then part of the total mass of the *system* Sun + Earth would be in that field.
« Last Edit: 26/01/2011 13:22:02 by lightarrow »
 

Offline jartza

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Why does heating increase mass?
« Reply #17 on: 26/01/2011 15:46:14 »
Mass is energy.
Mass is not additive.
Energy is additive.

Is there some kind of contradiction here?
 

Offline CPT ArkAngel

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Why does heating increase mass?
« Reply #18 on: 26/01/2011 17:45:00 »
no, "mass is energy" doesn't mean energy is mass.

There is no law of mass conservation. A particle and its antiparticle may annihilate each other and the result will be 2 photons with no mass at all. Only energy is conserved.
 

Offline jartza

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Why does heating increase mass?
« Reply #19 on: 26/01/2011 18:42:58 »
no, "mass is energy" doesn't mean energy is mass.

There is no law of mass conservation. A particle and its antiparticle may annihilate each other and the result will be 2 photons with no mass at all. Only energy is conserved.

Lightarrow says energy is mass, but mass is not energy
CPT AtkAngel says mass is energy, but energy is not mass
Some kind of scientist has said that heating increases mass


BUT everybody always says that mass is not conserved.

Now why is that? 




 

Offline lightarrow

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Why does heating increase mass?
« Reply #20 on: 26/01/2011 20:33:40 »
Mass is energy.
No, I haven't written exactly that, I have written that mass is energy *in a stationary system*.

Quote
Mass is not additive.
Energy is additive.
Is there some kind of contradiction here?
Here you are right, I should have been more precise, thank you for having noticed. What I intended with "mass" in the above statement is only the mass of the particles: if you have a system of n particles with mass m1, m2,...mn, the sum Σi=1n mi is not equal to the total mass of the system, in general, because there is also the energy of interaction among the particles, in general (no interaction --> sum of the masses = total mass). So, considering a closed system, the energy of interaction is mass and in this sense the mass is additive.
Let's make an example: the hydrogen atom. Measure accurately the proton's mass and the electron's mass and add the two. This sum is less than the atom's mass. The rest (as I already wrote) is in the fields of interaction between proton and electron. Usually, when we talk of a system of particles, we don't consider these fields' mass, but it has!
 

Offline lightarrow

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Why does heating increase mass?
« Reply #21 on: 26/01/2011 20:36:13 »
BUT everybody always says that mass is not conserved.
Not me.  :) At least I would specify the context.
Remember: energy in a stationary (= zero total momentum) system *is* mass.

Take a box with perfectly reflecting inner walls, weighs it: it has mass m. Inject light into it, so that its total energy has increased of E. Then weighs again the box in a super sensitive scale. Now the box' mass is m + E/c2, and there is no doubt about it.
« Last Edit: 26/01/2011 20:41:27 by lightarrow »
 

Offline Lamprey5

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Why does heating increase mass?
« Reply #22 on: 26/01/2011 20:40:49 »
total mass of a system of two particles with mass m1 and m2 is not m1 + m2.
Furthermore, where does the mass of a massive particle come from? Part of a mass of an atom is in the EM fields between nucleus and electrons. Most of the mass of a proton or a neutron is in the strong force fields between quarks.
A system of two photons not traveling in the exact same direction has mass.
A static electric field has mass.
...
The fact that mass, according to Oxford dictionary is "that which occupies space and possesses rest mass, especially as distinct from energy" is not very explicative...
Quote
How does energy and mass curve space-time similarly?
Because they are the same thing: the mass of a stationary system *is* that system's energy (divided by c2). The mass of a massive particle *is* the sum of all the energies of the different components of that particle, if it's made up of other things (energy is additive).

So if one were to put a hot gold bar in a bath of cold water, the mass of the gold bar would be less afterwards because it's atoms have less energy. But overall, the bar contains the same amount of matter in it.
If I understand that correctly, then I have another question: if most of the mass of a massive particle is in the strong force fields between quarks, how is this true? I mean, since an amount of matter and an amount of energy are physically different, or at least they do not appear the same, why do they have the same mass?
 

Offline lightarrow

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Why does heating increase mass?
« Reply #23 on: 26/01/2011 20:45:39 »
So if one were to put a hot gold bar in a bath of cold water, the mass of the gold bar would be less afterwards because it's atoms have less energy. But overall, the bar contains the same amount of matter in it.
Exactly. Just to be clear: "the same amount of matter" here means "the same number of elementary particles".

Quote
If I understand that correctly, then I have another question: if most of the mass of a massive particle is in the strong force fields between quarks, how is this true? I mean, since an amount of matter and an amount of energy are physically different, or at least they do not appear the same, why do they have the same mass?
Here with "matter" I presume you mean "particle". If you are able to confine an energy E of light in a so small region as that of an elementary particle...opla', you have some kind of particle with its mass m = E/c2. Compare with the box full of light of my previous post.
« Last Edit: 26/01/2011 20:47:42 by lightarrow »
 

Offline jartza

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Why does heating increase mass?
« Reply #24 on: 26/01/2011 22:14:38 »
BUT everybody always says that mass is not conserved.
Not me.  :)
 At least I would specify the context.
Remember: energy in a stationary (= zero total momentum) system *is* mass.

Take a box with perfectly reflecting inner walls, weighs it: it has mass m. Inject light into it, so that its total energy has increased of E. Then weighs again the box in a super sensitive scale. Now the box' mass is m + E/c2, and there is no doubt about it.

Well why not put this conservation law into use.
Let's put a proton and an electron in a box. After a while there is a
hydrogen atom and a photon in the box. We close the box carefully. Now
the mass of this box will not change. So from the law of conservation of mass:

mass of proton + mass of electron = mass of hydrogen atom + mass of photon in a box


let's solve mass of hydrogen atom from the equation:

mass of hydrogen atom = mass of proton + mass of electron - mass of photon in a box


We see that mass of hydrogen atom is SMALLER than mass of one proton and one electron.

(You said it's larger)
« Last Edit: 26/01/2011 22:23:44 by jartza »
 

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